What is the use of DTR pin in serial rs232 ?

[Livingston]

Hai Every body,

What is the use of DTR pin in serial rs232,

I want to integrate swipe card reader with 89c51

2nd pin of swipe card reader i am connecting to 10th pin of the controller.

5th pin of swipe card reader i am connecting to 20th pin of the controller.

9th pin of swipe card reader i am connecting to 40th pin of the controller.

4th pin of swipe card reader i mean the DTR where i will connect it with 89c51?

Please help me.

 

[mvs sarma]

Re: Rs232

please see this site

https://www.lammertbies.nl/comm/cable/RS-232.html

you get enough data.

Sarma

 

[laktronics]

Re: Rs232

Hi,
Is it a 9 pin RS232 connector signals that you are talking about? In that case the voltage levels of the signals will be +/- 12V, and the signals are inverted also. So, you need a MAX 232 like device to invert and change the levels to TTL, before it can be connected to the Microcontroller. Generally in such cases, pin 3 will be the TX output pin, which in turn after connecting through MAX 232, gets connected to the RX pin 10 of CPU. Pin 9, asper standard connection is Ring Indicator (RI), an output which is normally provided by modems. Before connecting it to Vcc, please check in your system it is not an output.
As far as DTR is concerned, it is a signal output which tells that the equipment is ready (Data Terminal Ready). So you should check this signal before reading any character from the unit, if the unit provides for DTR hand shaking, as it is generally called.
Regards,
Laktronics